The primary objectives of this research project are: 1) to extend our knowledge of the natural history of choroidal neovascular membranes in eyes with ocular histoplasmosis, senile macular degeneration and idiopathic macular degeneration, 2) to improve our information on the natural history of pre-existing chorioretinal scars in ocular histoplasmosis and macular drusen in senile macular degeneration, 3) to observe the rate of development of new chorioretinal scars in ocular histoplasmosis, and 4) to determine whether obliteration of choroidal neovascular membranes using argon laser photocoagulation is useful in preserving visual acuity in patients with ocular histoplasmosis, senile macular degeneration or idiopathic macular degeneration. Appropriate patients will be assigned to treatment or non-treatment categories by a randomized allocation process.